Music Grinder

How Children Interact with Toys:
- Children will rotate the handle and the music will play. The faster/harder they rotate the handle, the faster/louder the music will play. The sensor in the bottom of the whole will know how hard and fast the children rotate the handle.
Physical Principle Children will Learn:
- They will learn how rotation works. Also, by putting the handle into the hole, they will learn how convex(the handle) and concave(the whole) surfaces can match.
Construction cost, durability and safety:
- Construction cost: Roughly $10~30 (depending on the cost of the sensor).
- Durability: Children will be able to play with this practically forever as long as they replace the battery and don't throw the box.
- Safety: The corners and the edges of the box are rounded off so that there are no sharp corners or edges.